(Reuters) - Puma Biotechnology Inc said on Tuesday a European regulatory panel indicated it was unlikely to provide a positive opinion on the company’s breast cancer drug, sending its shares down 30 percent.

The setback comes six months after the U.S. Food and Drug Administration approved the experimental breast cancer drug that lowers the risk of the disease returning after initial treatment.

The Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency has pointed to a negative vote on the treatment, the company said in a statement.

Final drug approvals are up to the European Commission, but it generally follows the CHMP recommendation.

Puma shares were down 30 percent at $64 in extended trading.

Neratinib is designed to treat early-stage breast cancer in patients with the HER2 genetic mutation in which the tumor has been surgically removed, and had been previously treated with Roche’s Herceptin.

Breast cancer is the most frequently diagnosed cancer in women, with HER2-positive breast cancer accounting for 20 percent to 25 percent of breast cancer cases.